Implementation of Mediator Pattern

Recap the office example discussed in the previous section. Departments such as HR, Finance, and Technical need to communicate with one another. Direct communication between departments can be chaotic and ineffective.

Let's implement its solution through mediator pattern.

// Mediator Interface
interface DepartmentMediator {
    communicate(message: String, department: Department)
}

// Concrete Mediator
class OfficeMediator implements DepartmentMediator {
    HRDepartment hr
    FinanceDepartment finance
    TechnicalDepartment technical

    setHRDepartment(department: HRDepartment) {
        hr = department
    }

    setFinanceDepartment(department: FinanceDepartment) {
        finance = department
    }

    setTechnicalDepartment(department: TechnicalDepartment) {
        technical = department
    }

    communicate(message: String, department: Department) {
        if (department == hr) {
            finance.receiveMessage(message)
            technical.receiveMessage(message)
        } else if (department == finance) {
            // similar logic
        } else if (department == technical) {
            // similar logic
        }
    }
}

// Department Interface
interface Department {
    setMediator(mediator: DepartmentMediator)
    sendMessage(message: String)
    receiveMessage(message: String)
}

// Concrete Departments
class HRDepartment implements Department {
    DepartmentMediator mediator

    setMediator(mediator: DepartmentMediator) {
        this.mediator = mediator
    }

    sendMessage(message: String) {
        mediator.communicate(message, this)
    }

    receiveMessage(message: String) {
        // Handle received message
    }
}

// Similar classes for FinanceDepartment and TechnicalDepartment

// Client Code
main() {
    mediator = new OfficeMediator()
    hr = new HRDepartment()
    finance = new FinanceDepartment()
    technical = new TechnicalDepartment()

    mediator.setHRDepartment(hr)
    mediator.setFinanceDepartment(finance)
    mediator.setTechnicalDepartment(technical)

    hr.setMediator(mediator)
    finance.setMediator(mediator)
    technical.setMediator(mediator)

    hr.sendMessage("HR update for all departments")
}

• OfficeMediator (Concrete Mediator): Helps in communication between different departments. It has methods to set department references and a communicate method to route messages.
• Department (Interface): Each department in the office has a reference to a mediator for message exchange.HRDepartment, FinanceDepartment, TechnicalDepartment (Concrete Departments): Implement the Department interface. Each department uses the mediator to send messages to other departments.
• Client: Sets up the mediator and departments, and initiates communication.

Implementation